System for enabling user input and cursor control

ABSTRACT

A system for enabling user input and control of a cursor on a display device, the system comprising: a substrate having a position-coding pattern disposed on or in a surface thereof, said substrate having at least one input element and a discrete cursor zone; a sensing device comprising: an image sensor for optically imaging the position-coding pattern; and a processor configured for generating interaction data indicative of an interaction of the sensing device with the surface, said interaction data being indicative of a position or movement of the sensing device relative to the surface; communication means for communicating the interaction data to a computer system; and the computer system configured for: receiving the interaction data from the sensing device; retrieving a page description corresponding to said substrate; determining whether said sensing device is positioned within said cursor zone; interpreting movement of said sensing device within said cursor zone as a cursor movement and generating corresponding cursor control commands for said display device; and otherwise determining if said position or movement of said sensing device is within a zone of said at least one input element and initiating an action corresponding to said at least one input element.

FIELD OF INVENTION

The present invention relates to a method and system for reading aposition-coding pattern disposed on a surface. It has been developedprimarily to improve the functionality of sensing device used forreading the position-coding pattern.

COPENDING

The following applications have been filed by the Applicantsimultaneously with the present application:

NPZ025US NPZ026US NPZ027US NPZ028US NPZ030US NPZ031US

The disclosures of these co-pending applications are incorporated hereinby reference. The above applications have been identified by theirfiling docket number, which will be substituted with the correspondingapplication number, once assigned.

CROSS REFERENCES

The following patents or patent applications filed by the applicant orassignee of the present invention are hereby incorporated bycross-reference.

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BACKGROUND

The Applicant has previously described a method of enabling users toaccess information from a computer system via a printed substrate e.g.paper. The substrate has coded data printed thereon, which is read by anoptical sensing device when the user interacts with the substrate usingthe sensing device. A computer receives interaction data from thesensing device and uses this data to determine what action is beingrequested by the user. For example, a user may make handwritten inputonto a form or make a selection gesture around a printed item. Thisinput is interpreted by the computer system with reference to a pagedescription corresponding to the printed substrate.

It would be desirable to provide a broader range of functionalitiesavailable to the user via the sensing device. It would be particularlydesirable to provide this broader range of functionalities withoutintroducing a plethora of separate functional systems into the sensingdevice.

SUMMARY OF INVENTION

In a first aspect the present invention provides a system forcontrolling movement of a cursor on a display device, the systemcomprising:

-   -   a substrate having a position-coding pattern disposed on or in a        surface thereof;    -   a sensing device comprising:        -   an image sensor for optically imaging the position-coding            pattern; and        -   a processor configured for:            -   generating absolute motion data by determining a                plurality of absolute positions of the sensing device                relative to the surface using the imaged position-coding                pattern;            -   generating orientation data indicative of an orientation                of the sensing device relative to the substrate; and            -   using the orientation data to translate the absolute                motion data into relative motion data, said relative                motion data being indicative of relative motion of the                sensing device from the perspective of a user; and        -   communication means for communicating the relative motion            data to a computer system; and    -   the computer system configured for:        -   receiving said relative motion data from the sensing device;        -   interpreting said relative motion data as cursor movement;            and        -   generating cursor control commands for said display device.

Optionally, the relative motion data is indicative of relative positionchanges of the sensing device substantially from a perspective of auser, and irrespective of an orientation of said substrate.

Optionally, the position-coding pattern comprises a plurality of tags,each tag identifying a location on the surface and a rotationalorientation of the tag relative to the substrate, thereby enabling a yawof the sensing device relative to the substrate to be determined.

Optionally, said display device is selected from at least one of:

-   -   a display device associated with the computer system    -   a display device integral with the computer system; and    -   a display device remote from the computer system.

Optionally, said sensing device is operable in a plurality of modes,said plurality including a cursor mode and at least one other mode, andwherein the computer system is further configured for:

-   -   determining that said sensing device is operating in a cursor        mode.

Optionally, said at least one other mode is selected from the groupcomprising: a scroll mode; a hyperlinking mode; a searching mode; acontent-extraction mode; and a handwriting mode.

Optionally, said sensing device comprises a mode selector, and saidinteraction data comprises mode data indicative of said cursor mode.

Optionally, said mode selector comprises at least one of:

-   -   one or more mode buttons operable by a user; and    -   a sensor for detecting a force exerted by said sensing device on        said surface.

Optionally, said computer system is configured for retrieving storedmode data indicative of a most recent mode selected for said sensingdevice.

Optionally, said computer system is further configured for:

-   -   determining if said sensing device is positioned within a cursor        zone of said substrate, said cursor zone being activated by        determination of said cursor mode; and    -   interpreting relative motion of said sensing device only within        said cursor zone as said cursor movement.

Optionally, said computer system is further configured for:

-   -   determining if said sensing device is positioned within a scroll        zone of said substrate, said scroll zone being activated by        determination of said cursor mode; and    -   interpreting the interaction of said sensing device within said        scroll zone as a scroll action;    -   scrolling a page displayed on said display device according to        said scroll action.

Optionally, said computer system is configured for at least one of:

-   -   interpreting at least one absolute position of said sensing        device within said scroll zone to be indicative of a scroll        direction; and    -   interpreting relative motion of said sensing device within said        scroll zone to be indicative of a scroll direction.

Optionally, the position-coding pattern is further indicative of anidentity of the substrate and the interaction data comprises substrateidentity data.

Optionally, the substrate is a cursor control substrate and saidcomputer system is configured for using the substrate identity data toretrieve a cursor page description corresponding to said cursor controlsubstrate, said cursor page description comprising a cursor zone withinwhich the interaction of said sensing device is interpreted as saidcursor movement.

Optionally, said cursor page description comprises a scroll zone withinwhich the interaction of said sensing device is interpreted as a scrollaction, and wherein said computer system is configured to scroll a pagedisplayed on said display device according to said scroll action.

Optionally, said cursor control substrate has visible markingsindicating at least one of: said cursor zone, said scroll zone and ascroll direction.

Optionally, said scroll zone is located at an edge region of saidsubstrate.

In a further aspect the present invention provides a method ofcontrolling movement of a cursor on a display device via a substratehaving a position-coding pattern disposed on or in a surface thereof,said method comprising the steps of:

-   -   receiving, in a computer system, interaction data indicative of        an interaction of the sensing device with the substrate, said        interaction data comprising:        -   absolute motion data indicative of a plurality of absolute            positions of the sensing device relative to the surface; and        -   orientation data indicative of an orientation of the sensing            device relative to the substrate; and    -   using the orientation data to translate the absolute motion data        into relative motion data, said relative motion data being        indicative of position changes of the sensing device relative to        itself,    -   interpreting said relative motion data as cursor movement; and    -   generating cursor control commands for said display device.

In another aspect the present invention provides a sensing device forcontrolling movement of a cursor on a display device, said sensingdevice comprising:

-   -   an image sensor for optically imaging a position-coding pattern        disposed on or in a surface; and    -   a processor configured for:        -   generating absolute motion data by determining a plurality            of absolute positions of the sensing device relative to the            surface using the imaged position-coding pattern;        -   generating orientation data indicative of an orientation of            the sensing device relative to the substrate; and        -   using the orientation data to translate the absolute motion            data into relative motion data, said relative motion data            being indicative of relative motion of the sensing device            from the perspective of a user; and    -   communication means for communicating the relative motion data        to a computer system, thereby enabling the computer system to        generate cursor control commands using the relative motion data        for controlling movement of the cursor on the display device.

In a another aspect the present invention provides a computer system forcontrolling movement of a cursor on a display device via a substratehaving a position-coding pattern disposed on or in a surface thereof,said computer system being configured for:

-   -   receiving interaction data indicative of an interaction of the        sensing device with the substrate, said interaction data        comprising:        -   absolute motion data indicative of a plurality of absolute            positions of the sensing device relative to the surface; and        -   orientation data indicative of an orientation of the sensing            device relative to the substrate;    -   using the orientation data to translate the absolute motion data        into relative motion data, said relative motion data being        indicative of position changes of the sensing device relative to        itself;    -   interpreting said relative motion data as cursor movement; and    -   generating cursor control commands for said display device.

In a second aspect the present invention provides a sensing device forinteraction with a surface, said sensing device having automatic modeselection, said sensing device comprising:

-   -   an image sensor for imaging the surface and generating image        data;    -   a motion sensor configured for determining one or more relative        position changes of the sensing device;    -   a processor configured for:        -   receiving the image data; and        -   automatically selecting, using said image data, either an            interaction mode or a cursor mode for said sensing device;            and    -   communication means for transmitting either interaction data or        cursor data to a computer system, dependent on said selected        mode,        wherein said processor is configured to:    -   select the interaction mode and generate interaction data from        the image data if said image data indicates that said sensing        device is interacting with a first surface having a        position-coding pattern disposed thereon, said interaction data        being indicative of at least one absolute location of the        sensing device relative to the surface; and    -   select the cursor mode if said image data indicates that said        sensing device is interacting with a second surface lacking a        position-coding pattern, said cursor data being indicative of        said one or more relative position changes of the sensing        device.

Optionally, the motion sensor is selected from any one of the groupcomprising: at least one accelerometer; a mechanical mouse; an opticalmouse; and a point interferometry device.

Optionally, said motion sensor is an optical mouse utilizing at leastone of: a pattern-based optical mouse technique; a texture-based opticalmouse technique; and a laser-speckle-based optical mouse technique.

Optionally, the position-coding pattern of the first surface isindicative of a plurality of locations on the surface and of an identityof a region.

Optionally, in said interaction mode, said processor is configured fordetermining the identity of the region using the imaged position-codingpattern, and said interaction data is further indicative of the identityof the region.

Optionally, the identity of the region is coincident with an identity ofthe surface.

Optionally, the position-coding pattern is comprised of a plurality oftags, each tag identifying the identity of the surface and a location ofthe tag on the surface.

In a further aspect the present invention provides a system forinitiating an action corresponding to interaction of a sensing devicerelative to a surface, said system comprising:

(A) the sensing device comprising:

-   -   an image sensor for imaging the surface and generating image        data;    -   a motion sensor configured for determining one or more relative        position changes of the sensing device;    -   a processor configured for:        -   receiving the image data; and        -   automatically selecting, using said image data, either an            interaction mode or a cursor mode for said sensing device;            and    -   communication means for transmitting either interaction data or        cursor data to a computer system, dependent on said selected        mode,        wherein said processor is configured to:    -   select the interaction mode and generate interaction data if        said image data indicates that said sensing device is        interacting with a first surface having a position-coding        pattern disposed thereon, said interaction data being indicative        of an absolute location of the sensing device relative to the        surface; and    -   select the cursor mode if said image data indicates that said        sensing device is interacting with a second surface lacking a        position-coding pattern, said cursor data being indicative of        said one or more relative position changes of the sensing        device; and        (B) the computer system configured for:    -   receiving the interaction data and the cursor data from the        sensing device;    -   interpreting said interaction data to initiate an action        corresponding to said interaction with said surface; and    -   interpreting said cursor data to control movement of a cursor on        a display device.

Optionally, said action initiated by said interaction data is selectedfrom at least one of: hyperlinking; form-filling; searching; andcontent-extraction.

Optionally, the position-coding pattern of the first surface isindicative of a plurality of locations on the surface and of an identityof a region.

Optionally, in said interaction mode, said processor is configured fordetermining the identity of the region using the imaged position-codingpattern, and said interaction data is further indicative of the identityof the region.

Optionally, said computer system is configured to interpret saidinteraction data by the steps of:

-   -   identifying and retrieving a page description corresponding to        the first surface using the identity of the region;    -   determining a request using the retrieved page description and        the interaction data; and    -   initiating an action based on said request.

Optionally, the identity of the region is coincident with an identity ofthe surface.

Optionally, the position-coding pattern is comprised of a plurality oftags, each tag identifying the identity of the surface and a location ofthe tag on the surface.

Optionally, display device is selected from at least one of:

-   -   a display device associated with the computer system    -   a display device integral with the computer system; and    -   a display device remote from the computer system.

In a further aspect the present invention provides a method ofautomatically selecting a mode of a sensing device interacting with asurface, said sensing device comprising a motion sensor configured fordetermining one or more relative position changes of the sensing device,said method comprising the steps of:

-   -   imaging the surface and generating image data;    -   automatically selecting, using said image data, either an        interaction mode or a cursor mode for said sensing device; and    -   transmitting either interaction data or cursor data to a        computer system, dependent on said selected mode,        wherein:    -   the interaction mode is selected and the interaction data is        generated from the image data if said image data indicates that        said sensing device is interacting with a first surface having a        position-coding pattern disposed thereon, said interaction data        being indicative of at least one absolute location of the        sensing device relative to the surface; and    -   the cursor mode is selected and one or more relative position        changes of the sensing device are determined if said image data        indicates that said sensing device is interacting with a second        surface lacking a position-coding pattern, said cursor data        being indicative of said one or more relative position changes        of the sensing device.

In a further aspect the method further comprising the steps of:

-   -   receiving the interaction data in the computer system; and    -   interpreting said interaction data to initiate an action        corresponding to said interaction with said surface.

In another aspect the method further comprising the steps of:

-   -   receiving the cursor data from the sensing device;    -   interpreting said cursor data to control movement of a cursor on        a display device.

In a third aspect the present invention provides a system for enablingscrolling of a page displayed on a display device, the systemcomprising:

-   -   a substrate having a position-coding pattern disposed on or in a        surface thereof;    -   a sensing device operable in a plurality of modes including a        cursor mode, said sensing device comprising:        -   an image sensor for optically imaging the position-coding            pattern; and        -   a processor configured for generating interaction data            indicative of an interaction of the sensing device with the            surface, said interaction data being indicative of a            position or movement of the sensing device relative to the            surface;        -   communication means for communicating the interaction data            to a computer system; and    -   the computer system configured for:        -   receiving the interaction data from the sensing device;        -   determining that said sensing device is operating in a            cursor mode;        -   determining a scroll zone for said substrate;        -   determining if said sensing device is positioned within said            scroll zone;        -   interpreting said position or movement of said sensing            device within said scroll zone as a scrolling action; and        -   generating a scroll control command for said display device            so as to scroll said displayed page.

Optionally, the sensing device is operable in two or more modes selectedfrom the group comprising: said cursor mode; a hyperlinking mode; asearching mode; a content-extraction mode; and a handwriting mode.

Optionally, said sensing device comprises a mode selector, and saidinteraction data comprises mode data indicative of said cursor mode.

Optionally, said mode selector comprises at least one of:

-   -   one or more mode buttons operable by a user; and    -   a sensor for detecting a force exerted by said sensing device on        said surface.

Optionally, said computer system is configured for retrieving storedmode data indicative of a most recent mode selected for said sensingdevice.

Optionally, said computer system is configured for at least one of:

-   -   interpreting at least one absolute position of said sensing        device within said scroll zone to be indicative of a scroll        direction; and    -   interpreting movement of said sensing device within said scroll        zone to be indicative of a scroll direction.

Optionally, said scroll direction is selected from at least one of:

-   -   vertical scrolling;    -   horizontal scrolling; and    -   diagonal scrolling.

Optionally, said scroll zone is located at an edge region of saidsubstrate.

Optionally, said substrate comprises a plurality of scroll zones.

Optionally, said substrate comprises visible markings indicating atleast one of: said scroll zone and a scroll direction.

Optionally, said computer system is further configured for:

-   -   determining if said sensing device is positioned within a cursor        zone of said substrate;    -   interpreting movement of said sensing device as a cursor        movement; and    -   generating cursor control commands for said display device.

Optionally, said display device is selected from at least one of:

-   -   a display device associated with the computer system    -   a display device integral with the computer system; and    -   a display device remote from the computer system.

In a further aspect the system further comprising the display device.

Optionally, the position-coding pattern is further indicative of anidentity of the substrate and the interaction data comprises substrateidentity data.

Optionally, said computer system is configured for retrieving a pagedescription corresponding to said substrate using said substrateidentity.

Optionally, said computer is configured for retrieving said pagedescription if it is determined that said sensing device is notoperating in said cursor mode.

Optionally, said computer system is configured for:

-   -   using said position or movement of said sensing device together        with said retrieved page description to interpret said        interaction of said sensing device with said substrate; and    -   initiate an action corresponding to said interaction.

In another aspect the present invention provides a method of enablingscrolling of a page displayed on a display device via a substrate havingposition-coding pattern disposed in or on a surface thereof, said methodcomprising, in a computer system, the steps of:

-   -   receiving interaction data indicative of an interaction of the        sensing device with the substrate, said interaction data being        indicative of a position or movement of the sensing device        relative to the surface;    -   determining that said sensing device is operating in a cursor        mode;    -   determining a scroll zone for said substrate;    -   determining if said sensing device is positioned within a scroll        zone of said substrate;    -   interpreting said position or movement of said sensing device        within said scroll zone as a scrolling action; and    -   generating a scroll control command for said display device so        as to scroll said displayed page.

In a further aspect the present invention provides a computer system forcontrolling scrolling of a page displayed on a display device, saidcomputer system being configured for:

-   -   receiving interaction data indicative of an interaction of the        sensing device with a substrate having a position-coding pattern        disposed on or in a surface thereof, said interaction data being        indicative of a position or movement of the sensing device        relative to the surface;    -   determining that said sensing device is operating in a cursor        mode;    -   determining a scroll zone for said substrate;    -   determining if said sensing device is positioned within a scroll        zone of said substrate;    -   interpreting said position or movement of said sensing device        within said scroll zone as a scrolling action; and    -   generating a scroll control command for said display device so        as to scroll said displayed page.

In a fourth aspect the present invention provides a system for enablinguser input and control of a cursor on a display device, the systemcomprising:

-   -   a substrate having a position-coding pattern disposed on or in a        surface thereof, said substrate having at least one input        element and a discrete cursor zone;    -   a sensing device comprising:        -   an image sensor for optically imaging the position-coding            pattern; and        -   a processor configured for generating interaction data            indicative of an interaction of the sensing device with the            surface, said interaction data being indicative of a            position or movement of the sensing device relative to the            surface;        -   communication means for communicating the interaction data            to a computer system; and    -   the computer system configured for:        -   receiving the interaction data from the sensing device;        -   retrieving a page description corresponding to said            substrate;        -   determining whether said sensing device is positioned within            said cursor zone;        -   interpreting movement of said sensing device within said            cursor zone as a cursor movement and generating            corresponding cursor control commands for said display            device; and        -   otherwise determining if said position or movement of said            sensing device is within a zone of said at least one input            element and initiating an action corresponding to said at            least one input element.

Optionally, said at least one user input element is a GUI control buttonand said action is a corresponding GUI control action.

Optionally, said GUI control action is selected from the groupcomprising: scrolling; web browser control; page up; page down; cut;copy; paste; tab between GUI applications; launching of a GUIapplication; volume control; log off; sleep; and keyboard input.

Optionally, said substrate is an explicitly dedicated GUI controlsubstrate, said substrate comprising visible markings indicating saidcursor zone and said at least one GUI control button.

Optionally, said at least one input element is a hyperlink element, andsaid action is hyperlinking.

Optionally, said substrate comprises a scroll zone, and said computersystem is configured for interpreting a position or movement of saidsensing device within said scroll zone to be indicative of a scrollingaction.

Optionally, said computer system is configured for at least one of:

-   -   interpreting at least one absolute position of said sensing        device within said scroll zone to be indicative of a scroll        direction; and    -   interpreting movement of said sensing device within said scroll        zone to be indicative of a scroll direction.

Optionally, said scroll direction is selected from at least one of:

-   -   vertical scrolling;    -   horizontal scrolling; and    -   diagonal scrolling.

Optionally, said substrate comprises a plurality of scroll zones.

Optionally, said substrate comprises visible markings indicating atleast one of: said scroll zone and a scroll direction.

Optionally, said computer system is configured for interpreting movementof said sensing device within said cursor zone as relative movement.

Optionally, said computer system is configured for interpreting theposition or movement of said sensing device outside said cursor zone asan absolute position or movement relative to the surface.

Optionally, said display device is selected from at least one of:

-   -   a display device associated with the computer system    -   a display device integral with the computer system; and    -   a display device remote from the computer system.

In a further aspect the system further comprising the display device.

Optionally, the position-coding pattern is further indicative of anidentity of the substrate and the interaction data comprises substrateidentity data.

Optionally, said computer system is configured for retrieving the pagedescription corresponding to said substrate using said substrateidentity.

In another aspect the present invention provides a method of enablinguser input and control of a cursor on a display device via a substratehaving position-coding pattern disposed in or on a surface thereof, saidsubstrate having at least one input element and a discrete cursor zone,said method comprising, in a computer system, the steps of:

-   -   receiving interaction data indicative of an interaction of the        sensing device with the substrate, said interaction data being        indicative of a position or movement of the sensing device        relative to the surface;    -   retrieving a page description corresponding to said substrate;    -   determining whether said sensing device is positioned within        said cursor zone;    -   interpreting movement of said sensing device within said cursor        zone as a cursor movement and generating corresponding cursor        control commands for said display device; and    -   otherwise determining if said position or movement of said        sensing device is within a zone of said at least one input        element and initiating an action corresponding to said at least        one input element.

In a further aspect the present invention provides a computer system forenabling user input and control of a cursor on a display device via asubstrate having position-coding pattern disposed in or on a surfacethereof, said substrate comprising at least one input element and adiscrete cursor zone, said computer system being configured for:

-   -   receiving interaction data indicative of an interaction of the        sensing device with the substrate, said interaction data being        indicative of a position or movement of the sensing device        relative to the surface;    -   retrieving a page description corresponding to said substrate;    -   determining whether said sensing device is positioned within        said cursor zone;    -   interpreting movement of said sensing device within said cursor        zone as a cursor movement and generating corresponding cursor        control commands for said display device; and    -   otherwise determining if said position or movement of said        sensing device is within a zone of said at least one input        element and initiating an action corresponding to said at least        one input element.

BRIEF DESCRIPTION OF DRAWINGS

Preferred and other embodiments of the invention will now be described,by way of non-limiting example only, with reference to the accompanyingdrawings, in which:

FIG. 1 shows an embodiment of basic netpage architecture;

FIG. 2 is a schematic of a the relationship between a sample printednetpage and its online page description;

FIG. 3 shows an embodiment of basic netpage architecture with variousalternatives for the relay device;

FIG. 3A illustrates a collection of netpage servers, Web terminals,printers and relays interconnected via a network;

FIG. 4 is a schematic view of a high-level structure of a printednetpage and its online page description;

FIG. 5A is a plan view showing a structure of a netpage tag;

FIG. 5B is a plan view showing a relationship between a set of the tagsshown in FIG. 5 a and a field of view of a netpage sensing device in theform of a netpage pen;

FIG. 6A is a plan view showing an alternative structure of a netpagetag;

FIG. 6B is a plan view showing a relationship between a set of the tagsshown in FIG. 6 a and a field of view of a netpage sensing device in theform of a netpage pen;

FIG. 6C is a plan view showing an arrangement of nine of the tags shownin FIG. 6 a where targets are shared between adjacent tags;

FIG. 6D is a plan view showing the interleaving and rotation of thesymbols of the four codewords of the tag shown in FIG. 6 a;

FIG. 7 is a flowchart of a tag image processing and decoding algorithm;

FIG. 8 is a perspective view of a netpage pen and its associatedtag-sensing field-of-view cone;

FIG. 9 is a perspective exploded view of the netpage pen shown in FIG.8;

FIG. 10 is a schematic block diagram of a pen controller for the netpagepen shown in FIGS. 8 and 9;

FIG. 11 is a schematic view of a pen class diagram;

FIG. 12 is a schematic view of a document and page description classdiagram;

FIG. 13 is a schematic view of a document and page ownership classdiagram;

FIG. 14 is a schematic view of a terminal element specialization classdiagram;

FIG. 15 shows cursor control and scroll functions mapped onto anarbitrary page;

FIG. 16 shows an explicit cursor control and scroll page; and

FIG. 17 shows an explicit cursor control, scroll and keyboard page.

DETAILED DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

Note: Memjet™ is a trade mark of Silverbrook Research Pty Ltd,Australia.

In the preferred embodiment, the invention is configured to work withthe netpage networked computer system, a detailed overview of whichfollows. It will be appreciated that not every implementation willnecessarily embody all or even most of the specific details andextensions discussed below in relation to the basic system. However, thesystem is described in its most complete form to reduce the need forexternal reference when attempting to understand the context in whichthe preferred embodiments and aspects of the present invention operate.

In brief summary, the preferred form of the netpage system employs acomputer interface in the form of a mapped surface, that is, a physicalsurface which contains references to a map of the surface maintained ina computer system. The map references can be queried by an appropriatesensing device. Depending upon the specific implementation, the mapreferences may be encoded visibly or invisibly, and defined in such away that a local query on the mapped surface yields an unambiguous mapreference both within the map and among different maps. The computersystem can contain information about features on the mapped surface, andsuch information can be retrieved based on map references supplied by asensing device used with the mapped surface. The information thusretrieved can take the form of actions which are initiated by thecomputer system on behalf of the operator in response to the operator'sinteraction with the surface features.

In its preferred form, the netpage system relies on the production of,and human interaction with, netpages. These are pages of text, graphicsand images printed on ordinary paper, but which work like interactivewebpages. Information is encoded on each page using ink which issubstantially invisible to the unaided human eye. The ink, however, andthereby the coded data, can be sensed by an optically imaging sensingdevice and transmitted to the netpage system. The sensing device maytake the form of a clicker (for clicking on a specific position on asurface), a pointer having a stylus (for pointing or gesturing on asurface using pointer strokes), or a pen having a marking nib (formarking a surface with ink when pointing, gesturing or writing on thesurface). References herein to “pen” or “netpage pen” are provided byway of example only. It will, of course, be appreciated that the pen maytake the form of any of the sensing devices described above.

In one embodiment, active buttons and hyperlinks on each page can beclicked with the sensing device to request information from the networkor to signal preferences to a network server. In one embodiment, textwritten by hand on a netpage is automatically recognized and convertedto computer text in the netpage system, allowing forms to be filled in.In other embodiments, signatures recorded on a netpage are automaticallyverified, allowing e-commerce transactions to be securely authorized. Inother embodiments, text on a netpage may be clicked or gestured toinitiate a search based on keywords indicated by the user.

As illustrated in FIG. 2, a printed netpage 1 can represent ainteractive form which can be filled in by the user both physically, onthe printed page, and “electronically”, via communication between thepen and the netpage system. The example shows a “Request” formcontaining name and address fields and a submit button. The netpageconsists of graphic data 2 printed using visible ink, and coded data 3printed as a collection of tags 4 using invisible ink. The correspondingpage description 5, stored on the netpage network, describes theindividual elements of the netpage. In particular it describes the typeand spatial extent (zone) of each interactive element (i.e. text fieldor button in the example), to allow the netpage system to correctlyinterpret input via the netpage. The submit button 6, for example, has azone 7 which corresponds to the spatial extent of the correspondinggraphic 8.

As illustrated in FIGS. 1 and 3, a netpage sensing device 101, such asthe pen shown in FIGS. 8 and 9 and described in more detail below, worksin conjunction with a netpage relay device 601, which is anInternet-connected device for home, office or mobile use. The pen iswireless and communicates securely with the netpage relay device 601 viaa short-range radio link 9. In an alternative embodiment, the netpagepen 101 utilises a wired connection, such as a USB or other serialconnection, to the relay device 601.

The relay device 601 performs the basic function of relaying interactiondata to a page server 10, which interprets the interaction data. Asshown in FIG. 3, the relay device 601 may, for example, take the form ofa personal computer 601 a, a netpage printer 601 b or some other relay601 c.

The netpage printer 601 b is able to deliver, periodically or on demand,personalized newspapers, magazines, catalogs, brochures and otherpublications, all printed at high quality as interactive netpages.Unlike a personal computer, the netpage printer is an appliance whichcan be, for example, wall-mounted adjacent to an area where the morningnews is first consumed, such as in a user's kitchen, near a breakfasttable, or near the household's point of departure for the day. It alsocomes in tabletop, desktop, portable and miniature versions. Netpagesprinted on-demand at their point of consumption combine the ease-of-useof paper with the timeliness and interactivity of an interactive medium.

Alternatively, the netpage relay device 601 may be a portable device,such as a mobile phone or PDA, a laptop or desktop computer, or aninformation appliance connected to a shared display, such as a TV. Ifthe relay device 601 is not a netpage printer 601 b which printsnetpages digitally and on demand, the netpages may be printed bytraditional analog printing presses, using such techniques as offsetlithography, flexography, screen printing, relief printing androtogravure, as well as by digital printing presses, using techniquessuch as drop-on-demand inkjet, continuous inkjet, dye transfer, andlaser printing.

As shown in FIG. 3, the netpage sensing device 101 interacts with thecoded data on a printed netpage 1, or other printed substate such as alabel of a product item 251, and communicates, via a short-range radiolink 9, the interaction to the relay 601. The relay 601 sendscorresponding interaction data to the relevant netpage page server 10for interpretation. Raw data received from the sensing device 101 may berelayed directly to the page server 10 as interaction data.Alternatively, the interaction data may be encoded in the form of aninteraction URI and transmitted to the page server 10 via a user's webbrowser. Of course, the relay device 601 (e.g. mobile phone) mayincorporate a web browser and a display device.

Interpretation of the interaction data by the page server 10 may resultin direct access to information requested by the user. This informationmay be sent from the page server 10 to, for example, a user's displaydevice (e.g. a display device associated with the relay device 601). Theinformation sent to the user may be in the form of a webpage constructedby the page server 10 and the webpage may be constructed usinginformation from external web services 200 (e.g. search engines) orlocal web resources accessible by the page server 10. In somecircumstances, the page server 10 may access application computersoftware running on a netpage application server 13.

Alternatively, and as shown explicitly in FIG. 1, a two-step informationretrieval process may be employed. Interaction data is sent from thesensing device 101 to the relay device 601 in the usual way. The relaydevice 601 then sends the interaction data to the page server 10 forinterpretation with reference to the relevant page description 5. Then,the page server 10 forms a request (typically in the form of a requestURI) and sends this request URI back to the user's relay device 601. Aweb browser running on the relay device 601 then sends the request URIto a netpage web server 201, which interprets the request. The netpageweb server 201 may interact with local web resources and external webservices 200 to interpret the request and construct a webpage. Once thewebpage has been constructed by the netpage web server 201, it istransmitted to the web browser running on the user's relay device 601,which typically displays the webpage. This system architecture isparticularly useful for performing searching via netpages, as describedin our earlier U.S. patent application Ser. No. 11/672,950 filed on Feb.8, 2007 (the contents of which is incorporated by reference). Forexample, the request URI may encode search query terms, which aresearched via the netpage web server 201.

The netpage relay device 601 can be configured to support any number ofsensing devices, and a sensing device can work with any number ofnetpage relays. In the preferred implementation, each netpage sensingdevice 101 has a unique identifier. This allows each user to maintain adistinct profile with respect to a netpage page server 10 or applicationserver 13.

Digital, on-demand delivery of netpages 1 may be performed by thenetpage printer 601 b, which exploits the growing availability ofbroadband Internet access. Netpage publication servers 14 on the netpagenetwork are configured to deliver print-quality publications to netpageprinters. Periodical publications are delivered automatically tosubscribing netpage printers via pointcasting and multicasting Internetprotocols. Personalized publications are filtered and formattedaccording to individual user profiles.

A netpage pen may be registered with a netpage registration server 11and linked to one or more payment card accounts. This allows e-commercepayments to be securely authorized using the netpage pen. The netpageregistration server compares the signature captured by the netpage penwith a previously registered signature, allowing it to authenticate theuser's identity to an e-commerce server. Other biometrics can also beused to verify identity. One version of the netpage pen includesfingerprint scanning, verified in a similar way by the netpageregistration server.

Netpage System Architecture

Each object model in the system is described using a Unified ModelingLanguage (UML) class diagram. A class diagram consists of a set ofobject classes connected by relationships, and two kinds ofrelationships are of interest here: associations and generalizations. Anassociation represents some kind of relationship between objects, i.e.between instances of classes. A generalization relates actual classes,and can be understood in the following way: if a class is thought of asthe set of all objects of that class, and class A is a generalization ofclass B, then B is simply a subset of A. The UML does not directlysupport second-order modelling—i.e. classes of classes.

Each class is drawn as a rectangle labelled with the name of the class.It contains a list of the attributes of the class, separated from thename by a horizontal line, and a list of the operations of the class,separated from the attribute list by a horizontal line. In the classdiagrams which follow, however, operations are never modelled.

An association is drawn as a line joining two classes, optionallylabelled at either end with the multiplicity of the association. Thedefault multiplicity is one. An asterisk (*) indicates a multiplicity of“many”, i.e. zero or more. Each association is optionally labelled withits name, and is also optionally labelled at either end with the role ofthe corresponding class. An open diamond indicates an aggregationassociation (“is-part-of”), and is drawn at the aggregator end of theassociation line.

A generalization relationship (“is-a”) is drawn as a solid line joiningtwo classes, with an arrow (in the form of an open triangle) at thegeneralization end.

When a class diagram is broken up into multiple diagrams, any classwhich is duplicated is shown with a dashed outline in all but the maindiagram which defines it. It is shown with attributes only where it isdefined.

1 Netpages

Netpages are the foundation on which a netpage network is built. Theyprovide a paper-based user interface to published information andinteractive services.

A netpage consists of a printed page (or other surface region) invisiblytagged with references to an online description of the page. The onlinepage description is maintained persistently by the netpage page server10. The page description describes the visible layout and content of thepage, including text, graphics and images. It also describes the inputelements on the page, including buttons, hyperlinks, and input fields. Anetpage allows markings made with a netpage pen on its surface to besimultaneously captured and processed by the netpage system.

Multiple netpages (for example, those printed by analog printingpresses) can share the same page description. However, to allow inputthrough otherwise identical pages to be distinguished, each netpage maybe assigned a unique page identifier. This page ID has sufficientprecision to distinguish between a very large number of netpages.

Each reference to the page description is encoded in a printed tag. Thetag identifies the unique page on which it appears, and therebyindirectly identifies the page description. The tag also identifies itsown position on the page. Characteristics of the tags are described inmore detail below.

Tags are typically printed in infrared-absorptive ink on any substratewhich is infrared-reflective, such as ordinary paper, or in infraredfluorescing ink. Near-infrared wavelengths are invisible to the humaneye but are easily sensed by a solid-state image sensor with anappropriate filter.

A tag is sensed by a 2D area image sensor in the netpage sensing device,and the tag data is transmitted to the netpage system via the nearestnetpage relay device. The pen is wireless and communicates with thenetpage relay device via a short-range radio link. Tags are sufficientlysmall and densely arranged that the sensing device can reliably image atleast one tag even on a single click on the page. It is important thatthe pen recognize the page ID and position on every interaction with thepage, since the interaction is stateless. Tags are error-correctablyencoded to make them partially tolerant to surface damage.

The netpage page server 10 maintains a unique page instance for eachunique printed netpage, allowing it to maintain a distinct set ofuser-supplied values for input fields in the page description for eachprinted netpage.

The relationship between the page description, the page instance, andthe printed netpage is shown in FIG. 4. The printed netpage may be partof a printed netpage document 45. The page instance may be associatedwith both the netpage printer which printed it and, if known, thenetpage user who requested it.

2 Netpage Tags 2.1 Tag Data Content

In a preferred form, each tag identifies the region in which it appears,and the location of that tag within the region and an orientation of thetag relative to a substrate on which the tag is printed. A tag may alsocontain flags which relate to the region as a whole or to the tag. Oneor more flag bits may, for example, signal a tag sensing device toprovide feedback indicative of a function associated with the immediatearea of the tag, without the sensing device having to refer to adescription of the region. A netpage pen may, for example, illuminate an“active area” LED when in the zone of a hyperlink.

As will be more clearly explained below, in a preferred embodiment, eachtag typically contains an easily recognized invariant structure whichaids initial detection, and which assists in minimizing the effect ofany warp induced by the surface or by the sensing process. The tagspreferably tile the entire page, and are sufficiently small and denselyarranged that the pen can reliably image at least one tag even on asingle click on the page. It is important that the pen recognize thepage ID and position on every interaction with the page, since theinteraction is stateless.

In a preferred embodiment, the region to which a tag refers coincideswith an entire page, and the region ID encoded in the tag is thereforesynonymous with the page ID of the page on which the tag appears. Inother embodiments, the region to which a tag refers can be an arbitrarysubregion of a page or other surface. For example, it can coincide withthe zone of an interactive element, in which case the region ID candirectly identify the interactive element.

TABLE 1 Tag data Field Precision (bits) Page ID/Region ID 100 Tag ID/x-ycoordinates 16 Flags 4 Total 120

Each tag contains 120 bits of information, typically allocated as shownin Table 1. Assuming a maximum tag density of 64 per square inch, a16-bit tag ID supports a region size of up to 1024 square inches. Largerregions can be mapped continuously without increasing the tag IDprecision simply by using abutting regions and maps. The 100-bit regionID allows 2¹⁰⁰ (˜10³⁰ or a million trillion trillion) different regionsto be uniquely identified.

2.2 Tag Data Encoding

The 120 bits of tag data are redundantly encoded using a (15, 5)Reed-Solomon code. This yields 360 encoded bits consisting of 6codewords of 15 4-bit symbols each. The (15, 5) code allows up to 5symbol errors to be corrected per codeword, i.e. it is tolerant of asymbol error rate of up to 33% per codeword.

Each 4-bit symbol is represented in a spatially coherent way in the tag,and the symbols of the six codewords are interleaved spatially withinthe tag. This ensures that a burst error (an error affecting multiplespatially adjacent bits) damages a minimum number of symbols overall anda minimum number of symbols in any one codeword, thus maximising thelikelihood that the burst error can be fully corrected.

Any suitable error-correcting code can be used in place of a (15, 5)Reed-Solomon code, for example a Reed-Solomon code with more or lessredundancy, with the same or different symbol and codeword sizes;another block code; or a different kind of code, such as a convolutionalcode (see, for example, Stephen B. Wicker, Error Control Systems forDigital Communication and Storage, Prentice-Hall 1995, the contents ofwhich a herein incorporated by cross-reference).

2.3 Physical Tag Structure

The physical representation of the tag, shown in FIG. 5 a, includesfixed target structures 15, 16, 17 and variable data areas 18. The fixedtarget structures allow a sensing device such as the netpage pen todetect the tag and infer its three-dimensional orientation relative tothe sensor. The data areas contain representations of the individualbits of the encoded tag data.

To achieve proper tag reproduction, the tag is rendered at a resolutionof 256×256 dots. When printed at 1600 dots per inch this yields a tagwith a diameter of about 4 mm. At this resolution the tag is designed tobe surrounded by a “quiet area” of radius 16 dots. Since the quiet areais also contributed by adjacent tags, it only adds 16 dots to theeffective diameter of the tag.

The tag may include a plurality of target structures. A detection ring15 allows the sensing device to initially detect the tag. The ring iseasy to detect because it is rotationally invariant and because a simplecorrection of its aspect ratio removes most of the effects ofperspective distortion. An orientation axis 16 allows the sensing deviceto determine the approximate planar orientation of the tag due to theyaw of the sensor. The orientation axis is skewed to yield a uniqueorientation. Four perspective targets 17 allow the sensing device toinfer an accurate two-dimensional perspective transform of the tag andhence an accurate three-dimensional position and orientation of the tagrelative to the sensor.

All target structures are redundantly large to improve their immunity tonoise.

In order to support “single-click” interaction with a tagged region viaa sensing device, the sensing device must be able to see at least oneentire tag in its field of view no matter where in the region or at whatorientation it is positioned. The required diameter of the field of viewof the sensing device is therefore a function of the size and spacing ofthe tags.

Thus, if a tag has a circular shape, the minimum diameter of the sensorfield of view is obtained when the tags are tiled on a equilateraltriangular grid, as shown in FIG. 5 b.

2.4 Tag Image Processing and Decoding

The tag image processing and decoding performed by a sensing device suchas the netpage pen is shown in FIG. 7. While a captured image is beingacquired from the image sensor, the dynamic range of the image isdetermined (at 20). The center of the range is then chosen as the binarythreshold for the image 21. The image is then thresholded and segmentedinto connected pixel regions (i.e. shapes 23) (at 22). Shapes which aretoo small to represent tag target structures are discarded. The size andcentroid of each shape is also computed.

Binary shape moments 25 are then computed (at 24) for each shape, andthese provide the basis for subsequently locating target structures.Central shape moments are by their nature invariant of position, and canbe easily made invariant of scale, aspect ratio and rotation.

The ring target structure 15 is the first to be located (at 26). A ringhas the advantage of being very well behaved when perspective-distorted.Matching proceeds by aspect-normalizing and rotation-normalizing eachshape's moments. Once its second-order moments are normalized the ringis easy to recognize even if the perspective distortion was significant.The ring's original aspect and rotation 27 together provide a usefulapproximation of the perspective transform.

The axis target structure 16 is the next to be located (at 28). Matchingproceeds by applying the ring's normalizations to each shape's moments,and rotation-normalizing the resulting moments. Once its second-ordermoments are normalized the axis target is easily recognized. Note thatone third order moment is required to disambiguate the two possibleorientations of the axis. The shape is deliberately skewed to one sideto make this possible. Note also that it is only possible torotation-normalize the axis target after it has had the ring'snormalizations applied, since the perspective distortion can hide theaxis target's axis. The axis target's original rotation provides auseful approximation of the tag's rotation due to pen yaw 29.

The four perspective target structures 17 are the last to be located (at30). Good estimates of their positions are computed based on their knownspatial relationships to the ring and axis targets, the aspect androtation of the ring, and the rotation of the axis. Matching proceeds byapplying the ring's normalizations to each shape's moments. Once theirsecond-order moments are normalized the circular perspective targets areeasy to recognize, and the target closest to each estimated position istaken as a match. The original centroids of the four perspective targetsare then taken to be the perspective-distorted corners 31 of a square ofknown size in tag space, and an eight-degree-of-freedom perspectivetransform 33 is inferred (at 32) based on solving the well-understoodequations relating the four tag-space and image-space point pairs (seeHeckbert, P., Fundamentals of Texture Mapping and Image Warping, MastersThesis, Dept. of EECS, U. of California at Berkeley, Technical ReportNo. UCB/CSD 89/516, June 1989, the contents of which are hereinincorporated by cross-reference).

The inferred tag-space to image-space perspective transform is used toproject (at 36) each known data bit position in tag space into imagespace where the real-valued position is used to bilinearly interpolate(at 36) the four relevant adjacent pixels in the input image. Thepreviously computed image threshold 21 is used to threshold the resultto produce the final bit value 37.

Once all 360 data bits 37 have been obtained in this way, each of thesix 60-bit Reed-Solomon codewords is decoded (at 38) to yield 20 decodedbits 39, or 120 decoded bits in total. Note that the codeword symbolsare sampled in codeword order, so that codewords are implicitlyde-interleaved during the sampling process.

The ring target 15 is only sought in a subarea of the image whoserelationship to the image guarantees that the ring, if found, is part ofa complete tag. If a complete tag is not found and successfully decoded,then no pen position is recorded for the current frame. Given adequateprocessing power and ideally a non-minimal field of view 193, analternative strategy involves seeking another tag in the current image.

The obtained tag data indicates the identity of the region containingthe tag and the position of the tag within the region. An accurateposition 35 of the pen nib in the region, as well as the overallorientation 35 of the pen, is then inferred (at 34) from the perspectivetransform 33 observed on the tag and the known spatial relationshipbetween the image sensor (containing the optical axis of the pen) andthe nib (which typically contains the physical axis of the pen). Theimage sensor is usually offset from the nib.

2.5 Alternative Tag Structures

The tag structure described above is designed to support the tagging ofnon-planar surfaces where a regular tiling of tags may not be possible.In the more usual case of planar surfaces where a regular tiling of tagsis possible, i.e. surfaces such as sheets of paper and the like, moreefficient tag structures can be used which exploit the regular nature ofthe tiling.

FIG. 6 a shows a square tag 4 with four perspective targets 17. The tagrepresents sixty 4-bit Reed-Solomon symbols 47, for a total of 240 bits.The tag represents each one bit as a dot 48, and each zero bit by theabsence of the corresponding dot. The perspective targets are designedto be shared between adjacent tags, as shown in FIGS. 6 b and 6 c. FIG.6 b shows a square tiling of 16 tags and the corresponding minimum fieldof view 193, which must span the diagonals of two tags. FIG. 6 c shows asquare tiling of nine tags, containing all one bits for illustrationpurposes.

Using a (15, 7) Reed-Solomon code, 112 bits of tag data are redundantlyencoded to produce 240 encoded bits. The four codewords are interleavedspatially within the tag to maximize resilience to burst errors.Assuming a 16-bit tag ID as before, this allows a region ID of up to 92bits.

The data-bearing dots 48 of the tag are designed to not overlap theirneighbors, so that groups of tags cannot produce structures whichresemble targets. This also saves ink. The perspective targets thereforeallow detection of the tag, so further targets are not required. Tagimage processing proceeds as described in section 1.2.4 above, with theexception that steps 26 and 28 are omitted.

Although the tag may contain an orientation feature to allowdisambiguation of the four possible orientations of the tag relative tothe sensor, it is also possible to embed orientation data in the tagdata. For example, the four codewords can be arranged so that each tagorientation contains one codeword placed at that orientation, as shownin FIG. 6 d, where each symbol is labelled with the number of itscodeword (1-4) and the position of the symbol within the codeword (A-O).Tag decoding then consists of decoding one codeword at each orientation.Each codeword can either contain a single bit indicating whether it isthe first codeword, or two bits indicating which codeword it is. Thelatter approach has the advantage that if, say, the data content of onlyone codeword is required, then at most two codewords need to be decodedto obtain the desired data. This may be the case if the region ID is notexpected to change within a stroke and is thus only decoded at the startof a stroke. Within a stroke only the codeword containing the tag ID isthen desired. Furthermore, since the rotation of the sensing devicechanges slowly and predictably within a stroke, only one codewordtypically needs to be decoded per frame.

It is possible to dispense with perspective targets altogether andinstead rely on the data representation being self-registering. In thiscase each bit value (or multi-bit value) is typically represented by anexplicit glyph, i.e. no bit value is represented by the absence of aglyph. This ensures that the data grid is well-populated, and thusallows the grid to be reliably identified and its perspective distortiondetected and subsequently corrected during data sampling. To allow tagboundaries to be detected, each tag data must contain a marker pattern,and these must be redundantly encoded to allow reliable detection. Theoverhead of such marker patterns is similar to the overhead of explicitperspective targets. One such scheme uses dots positioned a variouspoints relative to grid vertices to represent different glyphs and hencedifferent multi-bit values (see Anoto Technology Description, AnotoApril 2000).

Additional tag structures are disclosed in U.S. Pat. No. 6,929,186(“Orientation-indicating machine-readable coded data”) filed by theapplicant or assignee of the present invention and the contents of whichis herein incorporated by reference.

2.6 Tag Map

Decoding a tag typically results in a region ID, a tag ID, and atag-relative pen transform. Before the tag ID and the tag-relative penlocation can be translated into an absolute location within the taggedregion, the location of the tag within the region must be known. This isgiven by a tag map, a function which maps each tag ID in a tagged regionto a corresponding location. The tag map class diagram is shown in FIG.22, as part of the netpage printer class diagram.

A tag map reflects the scheme used to tile the surface region with tags,and this can vary according to surface type. When multiple taggedregions share the same tiling scheme and the same tag numbering scheme,they can also share the same tag map.

The tag map for a region must be retrievable via the region ID. Thus,given a region ID, a tag ID and a pen transform, the tag map can beretrieved, the tag ID can be translated into an absolute tag locationwithin the region, and the tag-relative pen location can be added to thetag location to yield an absolute pen location within the region.

The tag ID may have a structure which assists translation through thetag map. It may, for example, encode Cartesian (x-y) coordinates orpolar coordinates, depending on the surface type on which it appears.The tag ID structure is dictated by and known to the tag map, and tagIDs associated with different tag maps may therefore have differentstructures.

With the tagging scheme described above, the tags usually function incooperation with associated visual elements on the netpage. Thesefunction as user interactive elements in that a user can interact withthe printed page using an appropriate sensing device in order for tagdata to be read by the sensing device and for an appropriate response tobe generated in the netpage system.

Additionally (or alternatively), decoding a tag may be used to provideorientation data indicative of the yaw of the pen relative to thesurface. The orientation data may be determined using, for example, theorientation axis 16 described above (Section 2.3) or orientation dataembedded in the tag data (Section 2.5).

3 Document and Page Descriptions

A preferred embodiment of a document and page description class diagramis shown in FIGS. 12 and 13.

In the netpage system a document is described at three levels. At themost abstract level the document 836 has a hierarchical structure whoseterminal elements 839 are associated with content objects 840 such astext objects, text style objects, image objects, etc. Once the documentis printed on a printer with a particular page size, the document ispaginated and otherwise formatted. Formatted terminal elements 835 willin some cases be associated with content objects which are differentfrom those associated with their corresponding terminal elements,particularly where the content objects are style-related. Each printedinstance of a document and page is also described separately, to allowinput captured through a particular page instance 830 to be recordedseparately from input captured through other instances of the same pagedescription.

The presence of the most abstract document description on the pageserver allows a copy of a document to be printed without being forced toaccept the source document's specific format. The user or a printingpress may be requesting a copy for a printer with a different page size,for example. Conversely, the presence of the formatted documentdescription on the page server allows the page server to efficientlyinterpret user actions on a particular printed page.

A formatted document 834 consists of a set of formatted pagedescriptions 5, each of which consists of a set of formatted terminalelements 835. Each formatted element has a spatial extent or zone 58 onthe page. This defines the active area of input elements such ashyperlinks and input fields.

A document instance 831 corresponds to a formatted document 834. Itconsists of a set of page instances 830, each of which corresponds to apage description 5 of the formatted document. Each page instance 830describes a single unique printed netpage 1, and records the page ID 50of the netpage. A page instance is not part of a document instance if itrepresents a copy of a page requested in isolation.

A page instance consists of a set of terminal element instances 832. Anelement instance only exists if it records instance-specificinformation. Thus, a hyperlink instance exists for a hyperlink elementbecause it records a transaction ID 55 which is specific to the pageinstance, and a field instance exists for a field element because itrecords input specific to the page instance. An element instance doesnot exist, however, for static elements such as textflows.

A terminal element 839 can be a visual element or an input element. Avisual element can be a static element 843 or a dynamic element 846. Aninput element may be, for example, a hyperlink element 844 or a fieldelement 845, as shown in FIG. 14. Other types of input element are ofcourse possible, such a input elements, which select a particular modeof the pen 101.

A page instance has a background field 833 which is used to record anydigital ink captured on the page which does not apply to a specificinput element.

In the preferred form of the invention, a tag map 811 is associated witheach page instance to allow tags on the page to be translated intolocations on the page.

4 The Netpage Network

In one embodiment, a netpage network consists of a distributed set ofnetpage page servers 10, netpage registration servers 11, netpage IDservers 12, netpage application servers 13, and netpage relay devices601 connected via a network 19 such as the Internet, as shown in FIG. 3.

The netpage registration server 11 is a server which recordsrelationships between users, pens, printers and applications, andthereby authorizes various network activities. It authenticates usersand acts as a signing proxy on behalf of authenticated users inapplication transactions. It also provides handwriting recognitionservices. As described above, a netpage page server 10 maintainspersistent information about page descriptions and page instances. Thenetpage network includes any number of page servers, each handling asubset of page instances. Since a page server also maintains user inputvalues for each page instance, clients such as netpage relays 601 sendnetpage input directly to the appropriate page server. The page serverinterprets any such input relative to the description of thecorresponding page.

A netpage ID server 12 allocates document IDs 51 on demand, and providesload-balancing of page servers via its ID allocation scheme.

A netpage relay 601 uses the Internet Distributed Name System (DNS), orsimilar, to resolve a netpage page ID 50 into the network address of thenetpage page server 10 handling the corresponding page instance.

A netpage application server 13 is a server which hosts interactivenetpage applications.

Netpage servers can be hosted on a variety of network server platformsfrom manufacturers such as IBM, Hewlett-Packard, and Sun. Multiplenetpage servers can run concurrently on a single host, and a singleserver can be distributed over a number of hosts. Some or all of thefunctionality provided by netpage servers, and in particular thefunctionality provided by the ID server and the page server, can also beprovided directly in a netpage appliance such as a netpage printer, in acomputer workstation, or on a local network.

5 The Netpage Pen

The active sensing device of the netpage system may take the form of aclicker (for clicking on a specific position on a surface), a pointerhaving a stylus (for pointing or gesturing on a surface using pointerstrokes), or a pen having a marking nib (for marking a surface with inkwhen pointing, gesturing or writing on the surface). A pen 101 isdescribed herein, although it will be appreciated that clickers andpointers may have similar features. The pen 101 uses its embeddedcontroller 134 to capture and decode netpage tags from a page via animage sensor. The image sensor is a solid-state device provided with anappropriate filter to permit sensing at only near-infrared wavelengths.As described in more detail below, the system is able to sense when thenib is in contact with the surface, and the pen is able to sense tags ata sufficient rate to capture human handwriting (i.e. at 200 dpi orgreater and 100 Hz or faster). Information captured by the pen may beencrypted and wirelessly transmitted to the printer (or base station),the printer or base station interpreting the data with respect to the(known) page structure.

The preferred embodiment of the netpage pen 101 operates both as anormal marking ink pen and as a non-marking stylus (i.e. as a pointer).The marking aspect, however, is not necessary for using the netpagesystem as a browsing system, such as when it is used as an Internetinterface. Each netpage pen is registered with the netpage system andhas a unique pen ID 61. FIG. 11 shows the netpage pen class diagram,reflecting pen-related information maintained by a registration server11 on the netpage network.

When the nib is in contact with a netpage, the pen determines itsposition and orientation relative to the page. The nib is attached to aforce sensor, and the force on the nib is interpreted relative to athreshold to indicate whether the pen is “up” or “down”. This allows aninteractive element on the page to be ‘clicked’ by pressing with the pennib, in order to request, say, information from a network. Furthermore,the force may be captured as a continuous value to allow, say, the fulldynamics of a signature to be verified.

The pen determines the position and orientation of its nib on thenetpage by imaging, in the infrared spectrum, an area 193 of the page inthe vicinity of the nib. It decodes the nearest tag and computes theposition of the nib relative to the tag from the observed perspectivedistortion on the imaged tag and the known geometry of the pen optics.Although the position resolution of the tag may be low, because the tagdensity on the page is inversely proportional to the tag size, theadjusted position resolution is quite high, exceeding the minimumresolution required for accurate handwriting recognition.

Pen actions relative to a netpage are captured as a series of strokes. Astroke consists of a sequence of time-stamped pen positions on the page,initiated by a pen-down event and completed by the subsequent pen-upevent. A stroke is also tagged with the page ID 50 of the netpagewhenever the page ID changes, which, under normal circumstances, is atthe commencement of the stroke.

Each netpage pen has a current selection 826 associated with it,allowing the user to perform copy and paste operations etc. Theselection is timestamped to allow the system to discard it after adefined time period. The current selection describes a region of a pageinstance. It consists of the most recent digital ink stroke capturedthrough the pen relative to the background area of the page. It isinterpreted in an application-specific manner once it is submitted to anapplication via a selection hyperlink activation.

Each pen has a current nib 824. This is the nib last notified by the pento the system. In the case of the default netpage pen described above,either the marking black ink nib or the non-marking stylus nib iscurrent. Each pen also has a current nib style 825. This is the nibstyle last associated with the pen by an application, e.g. in responseto the user selecting a color from a palette. The default nib style isthe nib style associated with the current nib. Strokes captured througha pen are tagged with the current nib style. When the strokes aresubsequently reproduced, they are reproduced in the nib style with whichthey are tagged.

The pen 101 may have one or more buttons 209. As described in U.S.application Ser. No. 11/672,950 filed on Feb. 8, 2007 (the contents ofwhich is herein incorporated by reference), the button(s) may be used todetermine a mode or behavior of the pen, which, in turn, determines howa stroke or, more generally, interaction data is interpreted by the pageserver 10.

Whenever the pen is within range of a relay device 601 with which it cancommunicate, the pen slowly flashes its “online” LED. When the pen failsto decode a stroke relative to the page, it momentarily activates its“error” LED. When the pen succeeds in decoding a stroke relative to thepage, it momentarily activates its “ok” LED.

A sequence of captured strokes is referred to as digital ink. Digitalink forms the basis for the digital exchange of drawings andhandwriting, for online recognition of handwriting, and for onlineverification of signatures.

The pen is typically wireless and transmits digital ink to the relaydevice 601 via a short-range radio link. The transmitted digital ink isencrypted for privacy and security and packetized for efficienttransmission, but is always flushed on a pen-up event to ensure timelyhandling in the printer.

When the pen is out-of-range of a relay device 601 it buffers digitalink in internal memory, which has a capacity of over ten minutes ofcontinuous handwriting. When the pen is once again within range of arelay device, it transfers any buffered digital ink.

A pen can be registered with any number of relay devices, but becauseall state data resides in netpages both on paper and on the network, itis largely immaterial which relay device a pen is communicating with atany particular time.

One embodiment of the pen is described in greater detail in Section 7below, with reference to FIGS. 8 to 10.

6 Netpage Interaction

The netpage relay device 601 receives data relating to a stroke from thepen 101 when the pen is used to interact with a netpage 1. The codeddata 3 of the tags 4 is read by the pen when it is used to execute amovement, such as a stroke. The data allows the identity of theparticular page to be determined and an indication of the positioning ofthe pen relative to the page to be obtained. Interaction data, typicallycomprising the page ID 50 and at least one position of the pen, istransmitted to the relay device 601, where it resolves, via the DNS, thepage ID 50 of the stroke into the network address of the netpage pageserver 10 which maintains the corresponding page instance 830. It thentransmits the stroke to the page server. If the page was recentlyidentified in an earlier stroke, then the relay device may already havethe address of the relevant page server in its cache. Each netpageconsists of a compact page layout maintained persistently by a netpagepage server (see below). The page layout refers to objects such asimages, fonts and pieces of text, typically stored elsewhere on thenetpage network.

When the page server receives the stroke from the pen, it retrieves thepage description to which the stroke applies, and determines whichelement of the page description the stroke intersects. It is then ableto interpret the stroke in the context of the type of the relevantelement.

A “click” is a stroke where the distance and time between the pen downposition and the subsequent pen up position are both less than somesmall maximum. An object which is activated by a click typicallyrequires a click to be activated, and accordingly, a longer stroke isignored. The failure of a pen action, such as a “sloppy” click, toregister may be indicated by the lack of response from the pen's “ok”LED.

Hyperlinks and form fields are two kinds of input elements, which may becontained in a netpage page description. Input through a form field canalso trigger the activation of an associated hyperlink. These types ofinput elements are described in further detail in the above-identifiedpatents and patent applications, the contents of which are hereinincorporated by cross-reference.

7 Detailed Netpage Pen Description 7.1 Pen Mechanics

Referring to FIGS. 8 and 9, the pen, generally designated by referencenumeral 101, includes a housing 102 in the form of a plastics mouldinghaving walls 103 defining an interior space 104 for mounting the pencomponents. Mode selector buttons 209 are provided on the housing 102.The pen top 105 is in operation rotatably mounted at one end 106 of thehousing 102. A semi-transparent cover 107 is secured to the opposite end108 of the housing 102. The cover 107 is also of moulded plastics, andis formed from semi-transparent material in order to enable the user toview the status of the LED mounted within the housing 102. The cover 107includes a main part 109 which substantially surrounds the end 108 ofthe housing 102 and a projecting portion 110 which projects back fromthe main part 109 and fits within a corresponding slot 111 formed in thewalls 103 of the housing 102. A radio antenna 112 is mounted behind theprojecting portion 110, within the housing 102. Screw threads 113surrounding an aperture 113A on the cover 107 are arranged to receive ametal end piece 114, including corresponding screw threads 115. Themetal end piece 114 is removable to enable ink cartridge replacement.

Also mounted within the cover 107 is a tri-color status LED 116 on aflex PCB 117. The antenna 112 is also mounted on the flex PCB 117. Thestatus LED 116 is mounted at the top of the pen 101 for good all-aroundvisibility.

The pen can operate both as a normal marking ink pen and as anon-marking stylus. An ink pen cartridge 118 with nib 119 and a stylus120 with stylus nib 121 are mounted side by side within the housing 102.Either the ink cartridge nib 119 or the stylus nib 121 can be broughtforward through open end 122 of the metal end piece 114, by rotation ofthe pen top 105. Respective slider blocks 123 and 124 are mounted to theink cartridge 118 and stylus 120, respectively. A rotatable cam barrel125 is secured to the pen top 105 in operation and arranged to rotatetherewith. The cam barrel 125 includes a cam 126 in the form of a slotwithin the walls 181 of the cam barrel. Cam followers 127 and 128projecting from slider blocks 123 and 124 fit within the cam slot 126.On rotation of the cam barrel 125, the slider blocks 123 or 124 moverelative to each other to project either the pen nib 119 or stylus nib121 out through the hole 122 in the metal end piece 114. The pen 101 hasthree states of operation. By turning the top 105 through 90° steps, thethree states are:

Stylus 120 nib 121 out;

Ink cartridge 118 nib 119 out; and

Neither ink cartridge 118 nib 119 out nor stylus 120 nib 121 out.

A second flex PCB 129, is mounted on an electronics chassis 130 whichsits within the housing 102. The second flex PCB 129 mounts an infraredLED 131 for providing infrared radiation for projection onto thesurface. An image sensor 132 is provided mounted on the second flex PCB129 for receiving reflected radiation from the surface. The second flexPCB 129 also mounts a radio frequency chip 133, which includes an RFtransmitter and RF receiver, and a controller chip 134 for controllingoperation of the pen 101. An optics block 135 (formed from moulded clearplastics) sits within the cover 107 and projects an infrared beam ontothe surface and receives images onto the image sensor 132. Power supplywires 136 connect the components on the second flex PCB 129 to batterycontacts 137 which are mounted within the cam barrel 125. A terminal 138connects to the battery contacts 137 and the cam barrel 125. A threevolt rechargeable battery 139 sits within the cam barrel 125 in contactwith the battery contacts. An contacts. An induction charging coil 140is mounted about the second flex PCB 129 to enable recharging of thebattery 139 via induction. The second flex PCB 129 also mounts aninfrared LED 143 and infrared photodiode 144 for detecting displacementin the cam barrel 125 when either the stylus 120 or the ink cartridge118 is used for writing, in order to enable a determination of the forcebeing applied to the surface by the pen nib 119 or stylus nib 121. TheIR photodiode 144 detects light from the IR LED 143 via reflectors (notshown) mounted on the slider blocks 123 and 124.

Rubber grip pads 141 and 142 are provided towards the end 108 of thehousing 102 to assist gripping the pen 101, and top 105 also includes aclip 142 for clipping the pen 101 to a pocket.

7.2 Pen Controller

The pen 101 is arranged to determine the position of its nib (stylus nib121 or ink cartridge nib 119) by imaging, in the infrared spectrum, anarea of the surface in the vicinity of the nib. It records the locationdata from the nearest location tag, and is arranged to calculate thedistance of the nib 121 or 119 from the location tab utilising optics135 and controller chip 134. The controller chip 134 calculates theorientation (yaw) of the pen using an orientation indicator in theimaged tag, and the nib-to-tag distance from the perspective distortionobserved on the imaged tag.

Utilising the RF chip 133 and antenna 112 the pen 101 can transmit thedigital ink data (which is encrypted for security and packaged forefficient transmission) to the computing system.

When the pen is in range of a relay device 601, the digital ink data istransmitted as it is formed. When the pen 101 moves out of range,digital ink data is buffered within the pen 101 (the pen 101 circuitryincludes a buffer arranged to store digital ink data for approximately12 minutes of the pen motion on the surface) and can be transmittedlater.

In Applicant's U.S. Pat. No. 6,870,966, the contents of which isincorporated herein by reference, a pen 101 having an interchangeableink cartridge nib and stylus nib was described. Accordingly, andreferring to FIG. 27, when the pen 101 connects to the computing system,the controller 134 notifies the system of the pen ID, nib ID 175,current absolute time 176, and the last absolute time it obtained fromthe system prior to going offline. The pen ID allows the computingsystem to identify the pen when there is more than one pen beingoperated with the computing system.

The nib ID allows the computing system to identify which nib (stylus nib121 or ink cartridge nib 119) is presently being used. The computingsystem can vary its operation depending upon which nib is being used.For example, if the ink cartridge nib 119 is being used the computingsystem may defer producing feedback output because immediate feedback isprovided by the ink markings made on the surface. Where the stylus nib121 is being used, the computing system may produce immediate feedbackoutput.

Since a user may change the nib 119, 121 between one stroke and thenext, the pen 101 optionally records a nib ID for a stroke 175. Thisbecomes the nib ID implicitly associated with later strokes.

Cartridges having particular nib characteristics may be interchangeablein the pen. The pen controller 134 may interrogate a cartridge to obtainthe nib ID 175 of the cartridge. The nib ID 175 may be stored in a ROMor a barcode on the cartridge. The controller 134 notifies the system ofthe nib ID whenever it changes. The system is thereby able to determinethe characteristics of the nib used to produce a stroke 175, and isthereby subsequently able to reproduce the characteristics of the strokeitself.

The controller chip 134 is mounted on the second flex PCB 129 in the pen101. FIG. 10 is a block diagram illustrating in more detail thearchitecture of the controller chip 134. FIG. 10 also showsrepresentations of the RF chip 133, the image sensor 132, the tri-colorstatus LED 116, the IR illumination LED 131, the IR force sensor LED143, and the force sensor photodiode 144.

The pen controller chip 134 includes a controlling processor 145. Bus146 enables the exchange of data between components of the controllerchip 134. Flash memory 147 and a 512 KB DRAM 148 are also included. Ananalog-to-digital converter 149 is arranged to convert the analog signalfrom the force sensor photodiode 144 to a digital signal.

An image sensor interface 152 interfaces with the image sensor 132. Atransceiver controller 153 and base band circuit 154 are also includedto interface with the RF chip 133 which includes an RF circuit 155 andRF resonators and inductors 156 connected to the antenna 112.

The controlling processor 145 captures and decodes location data fromtags from the surface via the image sensor 132, monitors the forcesensor photodiode 144, controls the LEDs 116, 131 and 143, and handlesshort-range radio communication via the radio transceiver 153. It is amedium-performance (˜40 MHz) general-purpose RISC processor.

The processor 145, digital transceiver components (transceivercontroller 153 and baseband circuit 154), image sensor interface 152,flash memory 147 and 512 KB DRAM 148 are integrated in a singlecontroller ASIC. Analog RF components (RF circuit 155 and RF resonatorsand inductors 156) are provided in the separate RF chip.

The image sensor is a 215×215 pixel CCD (such a sensor is produced byMatsushita Electronic Corporation, and is described in a paper byItakura, K T Nobusada, N Okusenya, R Nagayoshi, and M Ozaki, “A 1 mm 50k-Pixel IT CCD Image Sensor for Miniature Camera System”, IEEETransactions on Electronic Devices, Volt 47, number 1, January 2000,which is incorporated herein by reference) with an IR filter.

The controller ASIC 134 enters a quiescent state after a period ofinactivity when the pen 101 is not in contact with a surface. Itincorporates a dedicated circuit 150 which monitors the force sensorphotodiode 144 and wakes up the controller 134 via the power manager 151on a pen-down event.

The radio transceiver communicates in the unlicensed 900 MHz bandnormally used by cordless telephones, or alternatively in the unlicensed2.4 GHz industrial, scientific and medical (ISM) band, and usesfrequency hopping and collision detection to provide interference-freecommunication.

In an alternative embodiment, the pen incorporates an Infrared DataAssociation (IrDA) interface for short-range communication with a basestation or netpage printer.

7.3 Alternative Motion Sensor

In a further embodiment, the pen 101 includes a pair of orthogonalaccelerometers mounted in the normal plane of the pen 101 axis. Theaccelerometers 190 are shown in FIGS. 9 and 10 in ghost outline.

The provision of the accelerometers enables this embodiment of the pen101 to sense motion without reference to surface location tags. Eachlocation tag ID can then identify an object of interest rather than aposition on the surface. For example, if the object is a user interfaceinput element (e.g. a command button), then the tag ID of each locationtag within the area of the input element can directly identify the inputelement.

The acceleration measured by the accelerometers in each of the x and ydirections is integrated with respect to time to produce aninstantaneous velocity and position.

Since the starting position of the stroke may not be known, onlyrelative positions within a stroke are calculated. Although positionintegration accumulates errors in the sensed acceleration,accelerometers typically have high resolution, and the time duration ofa stroke, over which errors accumulate, is short.

It will be appreciated that a number of alternative (or additional)motion sensors may be employed in a Netpage pen 101. These typicallyeither measure absolute displacement or relative displacement. Forexample, an optical mouse that measures displacement relative to anexternal grid (see U.S. Pat. No. 4,390,873 and U.S. Pat. No. 4,521,772)measures absolute displacement, whereas a mechanical mouse that measuresdisplacement via the movement of a wheel or ball in contact with thesurface (see U.S. Pat. No. 3,541,541 and U.S. Pat. No. 4,464,652)measures relative displacement because measurement errors accumulate. Anoptical mouse that measures displacement relative to surface texture(see U.S. Pat. No. 6,631,218, U.S. Pat. No. 6,281,882, U.S. Pat. No.6,297,513 and U.S. Pat. No. 4,794,384), measures relative displacementfor the same reason. Motion sensors based on point interferometry (seeU.S. Pat. No. 6,246,482) or acceleration (see U.S. Pat. No. 4,787,051)also measure relative displacement. The contents of all US patentsidentified in the preceding paragraph relating to motion sensors areherein incorporated by reference.

7.4 GUI Control

As discussed in U.S. application Ser. No. 11/672,950 filed on Feb. 8,2007 (the contents of which is herein incorporated by reference), aNetpage pen 101 can be used to generate cursor control commands (i.e.typically mouse events) to allow seamless transitions between paperinteractions and on-screen interactions.

A computer system associated with the display device may receive cursorcontrol data (in the form of relative motion data) directly from the pen101, with the pen performing the necessary processing to generate thecursor control data from the interaction data. Alternatively, thecomputer system may receive interaction data as usual from the pen 101,and then generate cursor control commands for an associated displaydevice. Alternatively, the computer system may be a remote server whichreceives interaction data from the Netpage pen 101 and transmits cursorcontrol commands to a display device near the user (e.g. mobile phone).Any of these system architectures may support cursor control, althoughgeneration of cursor control commands in the pen is generally preferred.

As discussed in U.S. application Ser. No. 11/672,950, a cursor controlbehaviour can be selected in various ways, including via a momentary orpersistent mode switch. Alternatively, cursor control behaviour may alsobe automatically selected in the absence of a Netpage tag pattern, ifthe Netpage pen 101 incorporates a motion sensor that functions in theabsence of a tag pattern.

When positions generated by a Netpage pen 101 are intrinsicallyabsolute, such as when generated at least partially with reference to aNetpage tag pattern, then such positions can be trivially converted intoabsolute cursor control commands. The extent of the physical surfacewith which the sensing device is interacting is ideally mapped to theextent of a display device for the purposes of translating sensingdevice positions into cursor control commands.

However, cursor control commands commonly specify changes in positionrather than absolute positions—i.e. they are relative position changes.Absolute positions generated by a Netpage pen 101 by reading tags 4 maybe trivially converted into relative cursor control commands. Therelative scale of physical displacements of the Netpage reader andcorresponding screen displacements can be specified as a matter of userpreference, as well as whether the mapping is absolute or relative.

Although relative displacements of the pen 101 may be readily calculatedfrom absolute motion data, the implementation of cursor controlbehaviour from absolute positions is problematic in practice. In orderfor cursor control behaviour to appear ‘natural’ from a user'sperspective, cursor movements on a screen should always followsubstantially the movement of the pen 101 i.e. a left pen movement movesthe on-screen cursor to the left, an up pen movement moves the on-screencursor upwards etc. If a surface is orientated in the same way as adisplayed page, then on-screen cursor movements naturally reflectmovement of the pen 101. However, if the surface is upside down, thenthe on-screen cursor movements will be confusing and unnatural for theuser i.e. a left pen movement would move the on-screen cursor to theright.

Since users are not accustomed to orienting their traditional mousepadsin a certain way, they equally would not expect to orient theirNetpage-tagged surface in a certain way in order to invoke naturalcursor-control behaviour. In other words, it is desirable that thesurface and pen 101 should invoke natural mouse behaviour irrespectiveof how the surface is oriented.

This problem is solved by making used of the orientation informationcontained in the Netpage tags 4. As explained above in Sections 2.3 to2.5, the yaw of the pen 101 relative to the surface may be calculated bymaking use of this orientation information. If orientation data as wellas absolute motion data is received by a computer system, then thecomputer system can determine movement of the pen 101 relative to itselfby taking into account the yaw of the pen relative to the surface.Hence, movement of the pen, from a user's perspective, is substantiallytranslated into a corresponding on-screen cursor movement. In this way,the pen 101 may be used to control naturally the movement of the cursor,irrespective of the orientation of the surface.

Of course, when positions generated by a Netpage pen 101 areintrinsically relative, such as when they are generated using a relativemotion sensing mechanism (e.g. accelerometers, mechanical mouse, opticalmouse etc), then they map naturally to relative cursor control commands,again with a (potentially user-specified) scale factor.

Cursor control is a subset of graphical user interface (GUI) input andcontrol in general, including functions such as:

scrolling

web browser back/forward

page up/down etc.

cut/copy/paste

tab between GUI applications

launch specific GUI application (word processor, e-mail, web browser,etc.)

volume control (up/down/mute)

log off, sleep

keyboard entry in general

Scrolling can be supported in the conventional way via a scroll wheel onthe Netpage pen 101. It can also be provided implicitly as part of acursor control behaviour, when motion sensing at least partially occurswith reference to a Netpage tag pattern, by reserving part of the extentof each printed Netpage tag pattern as a scroll region. For example, theright-hand couple of inches of each printed Netpage might be reservedfor vertical scrolling, and the bottom couple of inches might bereserved for horizontal scrolling. This scroll region may be active whenit is determined that the pen 101 is operating in a cursor mode (forexample, by a mode switch on the pen).

Scrolling, like cursor control, can be absolute or relative, and can bespecified as a matter of user preference. As an alternative to separatevertical and horizontal scrolling areas, the dominant direction of theuser's scroll gesture within a single scroll region, relative to theorientation of the tag pattern, can also be used to distinguish verticalfrom horizontal scrolling. In order to allow diagonal scrolling, athreshold can be imposed on the vertical and horizontal components ofthe user's gesture to prevent inadvertent diagonal scrolling. As analternative to reserving a scroll region, one or two scroll modeselection switches can be provided on the pen 101.

FIG. 15 shows cursor control and scrolling functions mapped onto anarbitrary Netpage tagged page. The functions are only operative when theNetpage pen's cursor control behaviour is selected. The user readilylearns from experience that if the pen's cursor control behaviour isselected then cursor control and scrolling actions may be performed viacertain regions of any Netpage, even though there may be no explicitvisual indication of this functionality in the visible content of thepage. For example, scroll regions along a righthand and bottom edgeregion may be standard for any Netpage. These scroll regions would beactive only in the cursor mode.

FIG. 16 shows cursor control and scrolling functions explicitly mappedonto a page with a matching visual layout. Hence, the page shown in FIG.16 is a dedicated cursor control page, specifically tailored for GUIcontrol, including cursor control and scrolling actions. FIG. 17 showscursor control, scrolling functions and keyboard keys explicitly mappedonto a page with a matching visual layout. In the explicitly mappedcases the functions are self-selecting, and so can be operative in anypen behaviour.

Any function or key input can also be generated via a suitable Netpagetagged surface, either via tags specifically coded to indicatecorresponding functions or keys, or via a page description thatindicates corresponding functions or keys in the usual way. The formerhas the advantage that the input can be identified without consultingthe page description 5. This allows the user's relay device 601, whichmay commonly be the user's display device, to capture such input withoutrecourse to the Netpage server 10. In the latter case any function orkey input generated by the server with reference to the page descriptioncan be routed to the user's display device via the netpage architecture(see FIG. 1 and US Patent Publication No. 2006/025175, the contents ofwhich is herein incorporated by reference). This has the advantage thatit supports a display device that is separate from the relay device.

Printed controls can also be provided for selecting one-shot orpersistent modes, such as a scrolling mode. Printed controls may beselected via a typical netpage interaction, whereby a user selects aninteractive control element on a page, and this interaction isinterpreted as a mode selection in the computer system via the pagedescription.

The present invention has been described with reference to a preferredembodiment and number of specific alternative embodiments. However, itwill be appreciated by those skilled in the relevant fields that anumber of other embodiments, differing from those specificallydescribed, will also fall within the spirit and scope of the presentinvention. Accordingly, it will be understood that the invention is notintended to be limited to the specific embodiments described in thepresent specification, including documents incorporated bycross-reference as appropriate. The scope of the invention is onlylimited by the attached claims.

1. A system for enabling user input and control of a cursor on a displaydevice, the system comprising: a substrate having a position-codingpattern disposed on or in a surface thereof, said substrate having atleast one input element and a discrete cursor zone; a sensing devicecomprising: an image sensor for optically imaging the position-codingpattern; and a processor configured for generating interaction dataindicative of an interaction of the sensing device with the surface,said interaction data being indicative of a position or movement of thesensing device relative to the surface; communication means forcommunicating the interaction data to a computer system; and thecomputer system configured for: receiving the interaction data from thesensing device; retrieving a page description corresponding to saidsubstrate; determining whether said sensing device is positioned withinsaid cursor zone; interpreting movement of said sensing device withinsaid cursor zone as a cursor movement and generating correspondingcursor control commands for said display device; and otherwisedetermining if said position or movement of said sensing device iswithin a zone of said at least one input element and initiating anaction corresponding to said at least one input element.
 2. The systemof claim 1, wherein said at least one user input element is a GUIcontrol button and said action is a corresponding GUI control action. 3.The system of claim 2, wherein said GUI control action is selected fromthe group comprising: scrolling; web browser control; page up; pagedown; cut; copy; paste; tab between GUI applications; launching of a GUIapplication; volume control; log off; sleep; and keyboard input.
 4. Thesystem of claim 2, wherein said substrate is an explicitly dedicated GUIcontrol substrate, said substrate comprising visible markings indicatingsaid cursor zone and said at least one GUI control button.
 5. The systemof claim 1, wherein said at least one input element is a hyperlinkelement, and said action is hyperlinking.
 6. The system of claim 1,wherein said substrate comprises a scroll zone, and said computer systemis configured for interpreting a position or movement of said sensingdevice within said scroll zone to be indicative of a scrolling action.7. The system of claim 6, wherein said computer system is configured forat least one of: interpreting at least one absolute position of saidsensing device within said scroll zone to be indicative of a scrolldirection; and interpreting movement of said sensing device within saidscroll zone to be indicative of a scroll direction.
 8. The system ofclaim 7, wherein said scroll direction is selected from at least one of:vertical scrolling; horizontal scrolling; and diagonal scrolling.
 9. Thesystem of claim 1, wherein said substrate comprises a plurality ofscroll zones.
 10. The system claim 6, wherein said substrate comprisesvisible markings indicating at least one of: said scroll zone and ascroll direction.
 11. The system of claim 1, wherein said computersystem is configured for interpreting movement of said sensing devicewithin said cursor zone as relative movement.
 12. The system of claim 1,wherein said computer system is configured for interpreting the positionor movement of said sensing device outside said cursor zone as anabsolute position or movement relative to the surface.
 13. The system ofclaim 1, wherein said display device is selected from at least one of: adisplay device associated with the computer system a display deviceintegral with the computer system; and a display device remote from thecomputer system.
 14. The system of claim 1 further comprising thedisplay device.
 15. The system of claim 1, wherein the position-codingpattern is further indicative of an identity of the substrate and theinteraction data comprises substrate identity data.
 16. The system ofclaim 15, wherein said computer system is configured for retrieving thepage description corresponding to said substrate using said substrateidentity.
 17. A method of enabling user input and control of a cursor ona display device via a substrate having position-coding pattern disposedin or on a surface thereof, said substrate having at least one inputelement and a discrete cursor zone, said method comprising, in acomputer system, the steps of: receiving interaction data indicative ofan interaction of the sensing device with the substrate, saidinteraction data being indicative of a position or movement of thesensing device relative to the surface; retrieving a page descriptioncorresponding to said substrate; determining whether said sensing deviceis positioned within said cursor zone; interpreting movement of saidsensing device within said cursor zone as a cursor movement andgenerating corresponding cursor control commands for said displaydevice; and otherwise determining if said position or movement of saidsensing device is within a zone of said at least one input element andinitiating an action corresponding to said at least one input element.18. A computer system for enabling user input and control of a cursor ona display device via a substrate having position-coding pattern disposedin or on a surface thereof, said substrate comprising at least one inputelement and a discrete cursor zone, said computer system beingconfigured for: receiving interaction data indicative of an interactionof the sensing device with the substrate, said interaction data beingindicative of a position or movement of the sensing device relative tothe surface; retrieving a page description corresponding to saidsubstrate; determining whether said sensing device is positioned withinsaid cursor zone; interpreting movement of said sensing device withinsaid cursor zone as a cursor movement and generating correspondingcursor control commands for said display device; and otherwisedetermining if said position or movement of said sensing device iswithin a zone of said at least one input element and initiating anaction corresponding to said at least one input element.